An instant coupling device generally comprises a body that is axially subdivided into a joining section for joining to the circuit element and a connection section provided with a housing for receiving the pipe end and means for engaging therewith in leaktight manner. These means generally comprise arms that extend axially from the connection section, each having a free, gripper end for gripping the pipe end, each arm being elastically deformable between a gripping state and a state for releasing the pipe end. Some devices include a ring mounted on the body to slide between a position in which the ring surrounds the gripper ends of the arms to hold them in a gripping position, and an axially offset position in which the ring is disengaged from the gripper ends of the arms and allows them to bend.